Headers for combine harvesters sever crop material from the ground and convey the crop material to threshing, separating and cleaning assemblies. The headers used depend upon the crop to be harvested, farming practices employed and growing conditions.
Headers with a knife and guards for severing crop material from the ground are employed to harvest a number of different crops. The reciprocating knife has sections with cutting edges that cooperate with guards to shear crop material. A reel urges severed crop material toward a conveyor that conveys the severed crop material toward a thrashing assembly. The reel separates some seeds from the crop material. The knife sections move plant stalks toward the sides of guards and shake the plants. The shaking separates more seeds from the crop material. A substantial portion of the loose grain lands on the header or the knife due in part to forward movement of the header. If there is a substantial quantity of crop straw moving toward a header conveyor, a portion of the loose grain is carried by the straw to the thrashing assembly.
Crops such as wheat, rye and barley can generally be cut by the knife several inches above the ground. A portion of the loose grain separated by the reel and shaking by the reciprocating knife will slide into a header auger conveyor if the crop is cut several inches above the ground. When the knife is lowered to cut crop material as low as possible loose grain can slide forward and out of the header. The crop straw of some crops is relatively sticky and will sit on a header between the knife and the auger conveyor. Moving such material to the rear from the knife is a problem in some crop conditions.
Crops such as beans have pods that hold bean seeds. Bean pods grow on the stalks of most bean plants from near the top of the plant down to the ground. The pods near the ground and any seeds they contained are difficult to save. With beans like pintos and white beans for example, the plants are generally severed from their roots under the ground and then picked up with a pickup attachment on a combine. The attachment has some seed shatter loss. Occasionally wind will blow bean plants away after they are severed from their roots and before they are picked up. The severing process is an expensive additional operation.
Flexible headers have a cutter assembly that is able to flex up and down a few inches and follow the ground contour. Floating cutter bars move up and down over a larger vertical range than flexible headers. At least some floating cutter bars have plates that bridge a gap between a cutter assembly and an auger trough. These plates can lose some grain.
The flexible header and the floating cutter assembly both have a flat steel bar that extends from one end of the header to the other end. The flat steel bar is connected to the header frame by various structures. Sickle guards are bolted to a forward edge of the flat bar by bolts. Some guards have a single forwardly projecting member with a sickle section passage slot and a pointed forward tip. The rear portion of the guard extends under the flat bar and has an aperture that receives a bolt. The bolt clamps the guard to the bottom surface of the flat bar. Other guards have two forwardly projecting members with sickle section passages and forwardly projecting points. The rear portions of the two forwardly projecting members are connected by a transverse rib that is under the flat bar. Two bolts clamp a guard, with two forwardly projecting members, to the bottom of the flat bar. Guards with three forwardly projecting members are also employed on some headers. Rigid headers have an angle iron fixed to the lower forward portion of the header frame. The guards discussed above are clamped to the angle iron.
Air reels have been used in the past. Most air reels replace the bat reels or pickup reels with fingers that are used on headers for most small grain crops. Air reels generally have a horizontal tube supported by arms on the ends of a header that normally supports a driven reel shaft. A number of tubes extend downward from the horizontal tube and have nozzles on their lower ends that direct air downward and rearward toward the header conveyor. The horizontal tube is adjustable relative to the reel support arms in a fore and aft direction. The horizontal tube is also adjustable vertically by standard header reel lift cylinders. The nozzles on the lower ends of the vertical tubes are normally forward of and above the sickle guards. Air is directed to the nozzles from a blower through a pipe to the horizontal tube to the vertical tubes and to the nozzles. These air reels have been effective in short crop material. They generally do not do well in heavy crop material.
Attempts have been made to combine an air reel with a bat reel. The bat reel interferes with the air jets from the air nozzles and limit adjustment of the position of the nozzles. The reel and air nozzle combination also obstructs a harvester operator's view of the crop in front of the harvester. This can be a problem in fields with some rocks on the surface.
The connection between the guards and sickle assembly and the header will hold some seeds. Moving seeds caught by the header structure between the guards and the header conveyor can be difficult. An air stream close to the upper surface of the sickle sections can move seeds to the header conveyor. Air reels supported by reel support arms on the lateral ends of a header have had limited success saving free seeds that are held by the header structure forward of the header conveyor.
Most crop material that is dry for thrashing and that has been severed from the plant roots is relatively light weight and can be moved by a moderate wind. Wind will blow crop material with attached seeds out of a header at times. Some known air reels increase the problem thereby increasing grain losses in windy conditions.